The present invention relates generally to the field of mobile and handheld electronic devices with touch screens. More specifically, the present invention relates to a reduced keyboard, and a method associated for sliding capabilities and even more specifically to a method of recognizing a long word when input is a partial word trajectory of the word.
In the specification and the claims, which follow herein the terms “keyboard” and “keypad” are intended to mean a grouping of individual keys, as known in the art, used primarily for text input. “Reduced keyboard” and/or “reduced keypad”, as used hereinbelow in the specification and the claims, are intended to mean a keyboard and/or a keypad having reduced dimensions, such as found in, but not limited to, handheld electronic devices. In many (but not all) cases, a reduced keyboard is additionally a “virtual keyboard”, meaning a display of a keyboard on a touch screen—as opposed to a physical keyboard having physical keys.
In the specification and claims which follow, the following terms are identified and defined, in conjunction with a virtual keyboard:                “sliding capability” and/or “word sliding” is intended to mean a method of inputting successive letters in a word by moving a cursor, finger, pen, remote control, or other pointing device, which is maintained in contact with the virtual keyboard, from one letter to the next letter, using in a virtual keyboard. (In the case of a cursor or other pointing device, “maintained in contact” is typically accomplished by maintaining the left mouse button depressed while moving the cursor.)        “word tracing”, “word trajectory”, “sliding trajectory”, and/or simply “trajectory” and “tracing” are intended to mean the pattern resulting from word sliding. Typically, the trajectory is defined from when the cursor, finger, or other pointing device first makes contact with the virtual keyboard until when contact with the cursor, finger, or other pointing device and the keyboard is interrupted, as further described hereinbelow.        
Reduced keyboards with sliding capabilities have recently been widely applied for touch-screen devices, i.e. “virtual keyboards”. Presently, three patents (as well as subsequently issued and related patents by the respective inventors) are related to three respective products, namely: U.S. Pat. No. 7,199,786 (Suraqui, herein referred to as '786) having a related product called SlideIT® (which is also applicable to large screens with personal computer); U.S. Pat. No. 7,098,896 and subsequent patents by Kushler and Marsden, related to a product called Swype®; and U.S. Pat. No. 7,251,367 (Shumin Zhai) related to a product called Shapewriter®—respectively incorporated herein by reference. Two other patents have no currently known commercially related products, namely: U.S. Pat. No. 7,175,438 (Levy); and U.S. Pat. No. 7,250,938 (Kirkland et al.), which are incorporated herein by reference.
A sliding capability is very effective for short words (words usually having less than 6 or 7 letters) because the user can memorize a trajectory associated with the short word sliding. As a result, word sliding for short words is significantly faster than is for conventional word tapping (i.e. sequentially touching individual keys in a conventional, non-sliding manner) for the same short word. However in general, when considering long words (i.e. words usually having more than 6 or 7 letters) conventional tapping can be more efficient than word sliding.
Firstly, it is more difficult to memorize a sliding trajectory corresponding to a long word as compared to a trajectory for a short word. Secondly, sliding for a long word takes more time than word sliding for a shorter word. Additionally, as can intuitively be grasped, the risk of making errors in the trajectory increases with the length of a word/trajectory.
U.S. Pat. No. 7,895,518 (Kristenson) describes a system which displays words during tracing. However the displayed solutions are only the ones corresponding to the current trajectory (disambiguation). In some instances the system can recognize uncompleted words for instance when the user traces “th” the system can recognize “the” because the sub-word “th” is mapped to the word “the” in the lexicon. Such a method can be applied only for a limited number of words because it will request a huge amount of storage space, it is likely it could not work in real time and because of the huge size of the dictionary the number of wrong solutions could be unbearable. As an example in order to recognize the word “constitution” during all the step of the tracing process the sub-words “co”, “con”, “cons”, “const”, “consti”, “constit”, “constitu”, “constitut”, “constituti”, and “constitutio” should be part of the lexicon. The present invention works with the same dictionary needed for the regular sliding and does not request any additional new words or parts of words.
It is therefore desirable to create a keyboard input method in which long words may be efficiently and effectively input using word sliding by making predictions during the sliding process and giving the user the option to select the full long word at an early stage thus allowing time savings as well as having high reliability of prediction.